/*
 *  Licensed to the Apache Software Foundation (ASF) under one
 *  or more contributor license agreements.  See the NOTICE file
 *  distributed with this work for additional information
 *  regarding copyright ownership.  The ASF licenses this file
 *  to you under the Apache License, Version 2.0 (the
 *  "License"); you may not use this file except in compliance
 *  with the License.  You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing,
 *  software distributed under the License is distributed on an
 *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 *  KIND, either express or implied.  See the License for the
 *  specific language governing permissions and limitations
 *  under the License.
 */
package geb.collection

import java.util.function.Predicate

class FilteringIterator<T> implements Iterator<T> {

    private final Iterator<T> iterator
    private final Predicate<T> predicate

    private T nextObject
    private boolean nextObjectSet

    FilteringIterator(Iterator<T> iterator, Predicate<T> predicate) {
        this.iterator = iterator
        this.predicate = predicate
    }

    @Override
    boolean hasNext() {
        nextObjectSet || setNextObject()
    }

    @Override
    T next() {
        if (!nextObjectSet && !setNextObject()) {
            throw new NoSuchElementException()
        }
        nextObjectSet = false
        nextObject
    }

    private boolean setNextObject() {
        while (iterator.hasNext()) {
            T object = iterator.next()
            if (predicate.test(object)) {
                nextObject = object
                nextObjectSet = true
                return true
            }
        }
    }

}
